Sitting meditation means formal seated Zen meditation. Everybody understands what that is. But we must always keep a very wide view of meditation. If you keep a mind that is clear like space, then everything is meditation. There is walking meditation, chanting meditation, eating meditation. When your mind is clear like space, then your mind is not moving as situations constantly change. At that point, when you see, when you hear, when you smell, when you taste, when you touch, and when you think, everything is meditation, because everything is clearly reflected in your not-moving mind, just as it is.